CVE-2026-77164

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-77164
StatePUBLISHED
Assignerhackerone
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-18 02:17:07 UTC
Updated2026-09-18 02:17:07 UTC
DescriptionCircles' remote-instance signature verification fetches the attacker-supplied keyId URL before trust in the remote instance is established, and explicitly allows local/private addresses for this request, bypassing Nextcloud's core SSRF protections. The public, unauthenticated endpoints POST /apps/circles/event/ and POST /apps/circles/incoming/ reach this code path, allowing any unauthenticated user to force the server to issue a GET request to an internal address. The response body of the internal request is never returned to the requester, so this is blind SSRF: an attacker can determine whether an internal service is reachable, but cannot read its response contents through this endpoint alone.

Risk And Classification

Primary CVSS: v3.0 6.2 MEDIUM from [email protected]

CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Problem Types: CWE-918 | CWE-918 CWE-918 Server-Side Request Forgery (SSRF)

VersionSourceTypeScoreSeverityVector
3.0[email protected]Secondary6.2MEDIUMCVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
3.0CNADECLARED6.2MEDIUMCVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS v3.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Nextcloud Server affected 31.0.0 32.0.0 semver Not specified

References

ReferenceSourceLinkTags
hackerone.com/reports/3303283 [email protected] hackerone.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Balvant Chavda (0x0doteth) (en)

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